In industrial manufacture it is often required to inspect parts at a rapid rate to assure that they conform to a specified size and shape. This has been done at a slow rate by the use of optical comparators or by mechanical templates to compare a part to a master shape. Machine vision devices have also been used for this purpose. For example, the system shown in the patent to Rossol et al. U.S. Pat. No. 4,105,925 senses the boundaries of an object on a moving conveyor with the aid of structured lighting. Another arrangement uses a photocell to detect the presence of a moving object to trigger a two dimensional array camera. If a high resolution two dimensional camera is used to accurately capture the details of the moving object an extremely large amount of data is collected thereby requiring either extremely fast processing or a long delay to assimilate the data.